I don't think auto merge on name is worth it. And it's dangerous.

I have 3 different persons with the same name. And two of them are co-workers. (A middle name field would also be nice for this one, but that's a different story).

I don't mind the manual merge, as long as I only have to do it once!

But somehow the facebook plugin keeps un-merging random contacts.

Also the auto add contact when you send an email for a new email address is quite annoying.